Field emission of carbon nanotubes on anodic aluminum oxide template with controlled tube density

The tube number density of aligned carbon nanotubes (CNTs) grown over the nanoporous anodic aluminum oxide (AAO) template can be directly controlled by adjusting the CH4∕H2 feed ratio during the CNT growth. We ascribe the variation of the tube density as a function of the CH4∕H2 feed ratio to the kinetic competition between outgrowth of cobalt-catalyzed CNTs from the AAO pore bottom and deposition of the amorphous carbon (a-C) overlayer on the AAO template. A pore-filling ratio of 18% to 82% for the nanotubes overgrown out of nanopores on the AAO template can be easily achieved by adjusting the CH4∕H2 feed ratio. Enhanced field emission properties of CNTs were obtained by lowering the tube density on AAO. However, at a high CH4 concentration, a-C by-product deposit on the CNT surface can degrade the field emission property due to a high energy barrier and significant potential drop at the emission site.

[1]  Kenji Fukuda,et al.  Ordered Metal Nanohole Arrays Made by a Two-Step Replication of Honeycomb Structures of Anodic Alumina , 1995, Science.

[2]  Philip G. Collins,et al.  UNIQUE CHARACTERISTICS OF COLD CATHODE CARBON-NANOTUBE-MATRIX FIELD EMITTERS , 1997 .

[3]  C. Park,et al.  Preparation of Aligned Carbon Nanotubes with Prescribed Dimensions: Template Synthesis and Sonication Cutting Approach , 2002 .

[4]  Klaus Kern,et al.  Scanning field emission from patterned carbon nanotube films , 2000 .

[5]  J. Feuchtwanger,et al.  Structure, Thermal Stability, and Deformation of Multibranched Carbon Nanotubes Synthesized by CVD in the AAO Template , 2001 .

[6]  Enge Wang,et al.  Field emission of large-area and graphitized carbon nanotube array on anodic aluminum oxide template , 2003 .

[7]  N. Xu,et al.  Nanomaterials for field electron emission: preparation, characterization and application. , 2003, Ultramicroscopy.

[8]  I. Brodie,et al.  Vacuum microelectronic devices , 1994, Proc. IEEE.

[9]  L. Schlapbach,et al.  Electron field emission from phase pure nanotube films grown in a methane/hydrogen plasma , 1998 .

[10]  R. Baker,et al.  Catalytic growth of carbon filaments , 1989 .

[11]  Y. Saito,et al.  Field emission from carbon nanotubes and its application to electron sources , 2000 .

[12]  S. Akita,et al.  Barrier Effect on Field Emission from Stand-alone Carbon Nanotube , 2004 .

[13]  L. Schlapbach,et al.  Field emission properties of nanocrystalline chemically vapor deposited-diamond films , 1999 .

[14]  G. Amaratunga,et al.  Characterization of plasma-enhanced chemical vapor deposition carbon nanotubes by Auger electron spectroscopy , 2002 .

[15]  Martin Moskovits,et al.  Highly-ordered carbon nanotube arrays for electronics applications , 1999 .

[16]  U. Valdré,et al.  The enhancement factor and the characterization of amorphous carbon field emitters , 2001 .